In medieval mensural notation, the brevis was one of the shortest note lengths in use,[3] hence its name, which is the Latin etymon of "brief".[4][vague] In modern notation, a breve is commonly represented in either of two ways: by a hollow oval note head, like a whole note, with one or two vertical lines on either side, as on the left and right of the image, or as the rectangular shape also found in older notation, shown in the middle of the image.[5][6] Because it lasts longer than a bar in most modern time signatures in common use, the breve is rarely encountered except in English music, where the half-note is often used as the beat unit.[2][8]) Double whole rests are drawn as filled-in rectangles occupying the whole vertical space between the second and third lines from the top of the musical staff.In the mensural notation of the Renaissance, it was an alternative term for proportio dupla, which meant that the brevis was to be considered the unit of time (tactus), instead of the usual semibrevis.